Tunable magnetic and half-metallic properties of the two-dimensional electron gas in LaAlO3/SrTiO3(111) heterostructures.

Half-metallic materials have gained a lot of attention because of their unique properties and applications in spintronic devices. Despite the fact that these materials have been studied by several research groups there are very limited studies on their heterostructure (HS) systems. In the current study we have investigated the electronic and magnetic properties of (LaAlO3)6.5/(SrTiO3)2.5(111) HS using density functional theory (DFT) calculations. We demonstrate that the system exhibits a 100% spin-polarized two-dimensional electron gas (2DEG) which is extremely confined to the Ti 3d orbitals of the SrTiO3 layers. In particular, this system can keep its half-metallic properties under different in-plane strains from -3 to 2%. This property proves that this material has relatively stable half-metallic properties. In addition, the conducting and magnetic ground states of the system can also be tailored by changing in-plane strain and interfacial cation intermixing of La and Sr (Sr ⇔ La intermixing). By increasing the in-plane lattice parameters, this system has the ability to evolve from a nonmagnetic to a ferromagnetic metal and then to a half-metal and by further increasing the in-plane lattice parameter it becomes a ferromagnetic insulator. Sr ⇔ La intermixing can destroy the original half-metallic properties and the system exhibits an AFM Mott-type insulator phase. Our results demonstrate that the system has high potential for application in the field of spintronics, and opens the prospect of using LaAlO3/SrTiO3(111) HSs to explore quantum phase transitions.

The influence of porcine epidemic diarrhea virus on pig small intestine mucosal epithelial cell function.

Porcine epidemic diarrhea (PED) is a highly contagious, acute enteric tract infectious disease of pigs (Sus domesticus) caused by porcine epidemic diarrhea virus (PEDV). PED is characterized by watery diarrhea, dehydration, weight loss, vomiting and death. PEDV damages pig intestinal epithelial tissue, causing intestinal hyperemia and atrophy of intestinal villi, with formation of intestinal epithelial cell cytoplasmic vacuoles. Since pig small intestinal epithelial cells (IECs) are target cells of PEDV infection, IEC cells were utilized as a model for studying changes in cellular activities post-PEDV infection. Monitoring of Na+-K+-ATPase and Ca2+-Mg2+-ATPase activities demonstrated that PEDV infection decreased these activities. In addition, IECs proliferation was shown to decrease after PEDV infection using an MTT assay. Moreover, IECs apoptosis detected by flow cytometry with propidium iodide (PI) staining was clearly shown to increase relative to the control group. Meanwhile, animal experiments indicated that PEDV virulence for IEC cells was greater than viral virulence for Vero cells, although this may be due to viral attenuation after numerous passages in the latter cell line. Collectively, these studies revealed viral pathogenic mechanisms in PEDV-infected IECs and offer a theoretical basis for PEDV prevention and control.

Infection, genetic and virulence characteristics of porcine epidemic diarrhea virus in northwest China.

From September 2015 to May 2016, epidemic outbreaks of a diarrheal disease caused severe economic losses to the swine industry in northwest China. Typical clinical symptoms of the disease included severe diarrhea, vomiting, dehydration and death. In order to identify the pathogen, 27 intestinal samples were collected from dead piglets in Shaanxi, Gansu and Qinghai provinces and from Ningxia Hui Autonomous Region. All samples were tested using RT-PCR to detect rotavirus (RV), porcine epidemic diarrhea virus (PEDV) and transmissible gastroenteritis virus (TGEV). Twenty-five fecal samples were PEDV positive and five were TGEV positive; no piglets were infected with RV, indicating PEDV was the major pathogenic agent of viral diarrheal disease in these areas. Six strains were successfully isolated from positive samples and were serially passaged 40 times in Vero cells, with obvious cytopathic effects observed after 24 h post inoculation (hpi) and virus titers reaching 1.0 × 107 to 5.62 × 108. Sequence analysis ruled out that isolated strains were vaccine PEDV strains or strains derived from vaccine strains. Five strains belonged to classical strains, while one strain was a novel variant strain. The virulence of new novel variant strain SX1 and classical strain NX1 were tested in vivo using 10-day-old nursing piglets, revealing that both strains were highly pathogenic for piglets with destruction to small intestinal villi. Hematoxylin and eosin staining demonstrated markedly increased mucosal thickness, reduced villus length and villus/crypt (V/C) ratio in infected piglets. These pathological changes correlated with observed significantly reduced intestinal digestion and absorption functions that led to anorexia, dehydration, diarrhea and emaciation. Collectively, this study first reported the PEDV epidemic and phylogenetic analysis in northwest China and the results were important to understanding the infectivity, genetic characteristics, evolution and pathogenicity of PEDV strains, therefore, this experiment had important public health significance.